1. Field of the Invention
The present invention relates to an antenna connection unit, a received strength correction apparatus, and a capsule endoscope system.
2. Description of the Related Art
An endoscope is widely used as a medical observation instrument that is introduced into a subject to observe inside a body cavity of the subject. In recent years, a swallowable endoscope (capsule endoscope) has been developed, which includes an imaging device and a communication device that wirelessly transmits image data captured by the imaging device, in a capsule-shaped casing.
The capsule endoscope is swallowed from a mouth of the subject to observe inside the body cavity, moves inside organs such as an esophagus, a stomach, and a small intestine following their peristaltic motion until it is naturally excreted from the subject, and sequentially captures images while moving inside the organs. Image data captured by the capsule endoscope inside the body cavity while the capsule endoscope moves inside the body cavity is sequentially transmitted to outside the body by a wireless transmission and accumulated in a memory provided inside or outside an external receiving device or displayed on a display provided on the receiving device.
A doctor or a nurse can load the image data accumulated in the memory to an information processing apparatus via a cradle into which the receiving device is plugged and perform a diagnosis of the subject based on the image displayed on a display of the image processing apparatus or the image displayed on the display of the receiving device.
When receiving a wireless signal from the capsule endoscope, in the receiving device, in general, a plurality of receiving antennas is arranged outside the subject in a distributed manner, one antenna having the strongest received strength is selected, and the wireless signal is received by the selected antenna. For example, a receiving device that switches a reception among a plurality of antennas arranged outside a subject and detects a position of a capsule endoscope inside the subject, which is a transmission source of the wireless signal, based on the electric field strength received by each of the antennas has been known (see, for example, Japanese Laid-open Patent Publication No. 2003-000608). In addition, a technique for detecting a position of a capsule endoscope by estimating the position from reception power of a plurality of receiving antennas has been known.